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200+ free browser tools from Certoflow. No sign-up, no uploads — just open and use.
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Education & Grade Calculators
GPA, semester grades, final exam targets, and online test grading — our most-used student tools.
GPA Calculator — Free College & Semester GPA Tool
GPA from letter grades and credit hours.
Semester Grade Calculator — Free Weighted Course Grade Tool
Weighted semester grade from category scores.
Exam Calculator — Final Grade & Score Needed
Exam score needed for your target grade.
Easy Grader — Free Online Test Grader & Score Checker
Online grading with letter grade output.
Percentage Calculator — Free Exam Score & Grade Math
Percent of, what percent, and percent change.
Grade Scale Converter
Convert letter grades, percentages, and GPA.
SEO & Meta Tag Tools
Meta title and description checkers, SERP previews, and tag generators — top tools for marketers and site owners.
Free Meta Description Checker — Length & Character Count
Check meta description character count.
Free Meta Title Length Checker — SEO Title Tag Tool
Check SEO title length and pixels.
SERP Snippet Preview — Free Google Search Result Simulator
Preview Google search snippets.
Meta Tags Generator
Generate title and meta description HTML.
Open Graph Tag Generator
Generate og: meta tags.
Canonical Tag Generator
Generate canonical link tags.
Trending Tools
High-demand tools across SEO, PDF, and gaming — updated from search trends.
SERP Snippet Preview — Free Google Search Result Simulator
Preview Google search snippets.
SEO ToolsTwitter Card Generator
Generate twitter:card meta tags.
SEO ToolsRobots.txt Generator
Build robots.txt crawl rules.
Gaming ToolsRoblox Tax Calculator — Free Robux Fee & Marketplace Tax
Robux after 30% marketplace fee.
PDF ToolsMerge PDF
Combine PDFs into one file.
Education ToolsEasy Grader — Free Online Test Grader & Score Checker
Online grading with letter grade output.
Popular Tools
Top-performing tools across SEO, education, and gaming — based on search demand.
Free Meta Description Checker — Length & Character Count
Check meta description character count.
Free Meta Title Length Checker — SEO Title Tag Tool
Check SEO title length and pixels.
Semester Grade Calculator — Free Weighted Course Grade Tool
Weighted semester grade from category scores.
GPA Calculator — Free College & Semester GPA Tool
GPA from letter grades and credit hours.
Exam Calculator — Final Grade & Score Needed
Exam score needed for your target grade.
Roblox Tax Calculator — Free Robux Fee & Marketplace Tax
Robux after 30% marketplace fee.
Recently Added
Latest tools added to Certoflow.
Password Strength Checker — Free Security Tool
Score password strength with tips.
Developer ToolsPassphrase Generator — Secure Random Passphrases
Random word passphrases.
Developer ToolsAPI Key Generator — Random Hex Keys
Random hex API keys.
Developer ToolsRandom Bytes Generator — Hex Output
Random bytes as hex.
Developer ToolsHMAC SHA256 Generator — Free Online Tool
HMAC-SHA256 signature.
Developer ToolsCORS Header Generator — Access-Control Headers
CORS response headers.
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Browse Categories
Explore tools organized by what you need to do.
Developer Tools
JSON formatters, encoders, hash generators, and utilities built for developers.
5 toolsDate & Time Tools
Unix timestamps, timezone helpers, and date calculators that run in your browser.
22 toolsEducation Tools
Free grade calculators, GPA tools, exam score planners, and study helpers for students and teachers. Semester grades, online grading, and 4.0 scale conversions — all in your browser.
39 toolsGaming Tools
Dice rollers, randomizers, and quick utilities for tabletop and video games.
20 toolsText Tools
Word counters, case converters, and text manipulation utilities.
20 toolsImage Tools
Compress, resize, and convert images directly in your browser.
10 toolsColor Tools
Hex and RGB converters, contrast checkers, and CSS gradient generators.
10 toolsPDF Tools
Merge, split, convert, and compress PDF files entirely in your browser.
16 toolsSEO Tools
Meta tag generators, SERP previews, robots.txt builders, and schema markup helpers.